Machines for processing leather



April 3, 1956 scHODEL 2,740,283

MACHINES FOR PROCESSING LEATHER Filed June- 25, 1954 4 Sheets-Sheet 1[Am s7 6 0 1 505;

5 XMM April 3, 1956 E. scHODEL 2,740,283

MACHINES FOR PROCESSING LEATHER Filed June 25, 1954 4 Sheets-Sheet 2Fig. 3

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United States Patent Q MACHINES FGR PROESING LEATHER Ernst Schiidel,Dusseldorf, Germany, assignor to Rheinmetal! Aktiengesellschaft,Dusseldorf, Germany Application lune 25, 1954, Serial No. 439,379

Claims priority, application Germany July 2, 1953 8 Claims. (Cl. 6-34)The present invention relates to a universal staking and finishingmachine for the processing, and more especially the softening, ofleather or pelts, having a rotating knife cylinder; a resilient pressuredevice for the work-piece adapted to be moved against the knifecylinder, and a workpiece holding device or starting frame adjustable ina vertical direction.

In machines of this type the processing of the leather, that is to saythe staking, sleeking and buffing, is performed by the knife cylinderrotating at considerable speed and having the individual knives (stakingblades) arranged in oppositely directed spirals from the centre of thecylinder towards each end thereof. The leather or pelt to be processedis clamped with one edge in the workpiece holder or staking frame, andis pressed by means of the resilient pressure device, such as, forexample, a leather pad, with its flesh side against the cylinder so thatthe blades, inclined to the left and to the right respectively, stakethe leather sideways. Since, at the same time, the staking frame isreciprocated in the vertical direction all portions of the workpiececome successively within the reach of the knife cylinder. As a result,the leather is intensively subjected to thorough working up in alldirections.

It is an object of the invention to provide a machine of the typereferred to which can be operated with a minimum of energy and whichenables the material to be worked up very gently. More especially it isdirected to enabling the operating components, that is to say thestaking frame and the pressure device, to be controlled by touch. Thus,for example, a slight pressure on the control lever of the pressuredevice should cause the workpiece to be pressed gently, and strongerpressure should cause it to be pressed hard against the knife cylinder.In a similar manner a slight pressure on the control lever of thestaking frame drive should cause the frame to rise slowly and a strongpressure should cause the frame to rise rapidly. The invention furtheraims at providing a compact arrangement and simple installation of themachine, smooth operation of the drives for the staking frame and thepressure device, and ready adaptability of the machine to the differentqualities of leathers and/r pelts to be processed.

According to the invention the pressure device and the workpiece holderare operated hydraulically through suitably designed working cylinders,each cylinder being connected with a pressure fluid circulating systemseparately connected to a fluid containing tank and adapted to beindividually adjusted by means of a throttling means.

This special arrangement of the hydraulic system resu ts, in the firstplace, in the machine operation being simple and requiring almost noexertion at all on the part of the operator and the possibility ofhandling the controls by touch. Since the pressure fluid circulatingsystem for the working cylinder of the staking frame is completelyindependent of the system operating the working cylinder of the pressuredevice, each cylinder can be op- 2,743,283 Patented Apr. 3, 1956 eratedunder the most advantageous hydraulic conditions so that the designerhas a completely free hand in designing these elements wherebyparticularly economical construction and working is ensured.

The invention will be described in more detail with reference to oneembodiment thereof shown in the drawings in which-- Fig. 1 is anelevation, showing in diagrammatic form the essential components of auniversal staking machine according to the invention, 7

Fig. 2 is a plan view of the staking frame and the knife cylinder,likewise shown diagrammatically,

Fig. 3 is an elevation, partly in section, of a valve box with controlvalve, control lever and associated operating links, I

Fig. 4 is a longitudinal section of a control valve,

Fig. 5 shows in longitudinal section the working cylinder for theoperation of the staking frame, with the components retracted (stakingframe in the lower position), and

Fi. 6 is a longitudinal section through the working cylinder for thepressure device, with the components likewise fully retracted, that isto say with the pressure device removed from the knife cylinder.

The machine as shown in the drawings comprises an upright frame 1 oneither side of which the knife cylinder 2 is rotatably supported inpedestals (not shown in drawing). The knife cylinder (Fig. 2,) is madeup of a basic body of, for example, hexagonal cross-section, pro

vided with staking knives 3, 4 arranged in two sets start ing from thecentre of the cylinder in a lefthand and a righthand spiralrespectively. The'knife cylinder 2 is 1-0- tated by an electric motor(not shown in drawing) through multiple V-belts or the like.

The pressure device which presse the workpiece to be processed againstthe knife cylinder comprises a pad in the form of an endless leatherbelt 5 slung about a frame-like carrier 6. Compression springs 7, thetension of which can be adjusted by meansof threaded nuts 8, maintain aneven, predetermined tension of the leather belt 5. Rigidly connectedwith the carrier frame 6 there is a shaft 9 which in turn is rotatablysupported in bearings (not shown in drawing) attached to the machineframe 1. This shaft 9 is further rigidly connected with a lever 10 onthe free end of which the plunger 12 of the hydraulically operatedcylinder (see also Fig. 6) acts through a ball-and-socket joint 11, 11a,the cylinder body of said Working cylinder being indicated at 13 andFig. 1. The bottom end of the cylinder body is connected through a ball14 and socket 15 with a fixed part 16 of the machine frame. When theplunger 12 is moved outwardly from the cylinder in a manner to bedescribed below, the lever 10, together with the frame 6 and thepressure pad 5, swivels correspondingly about the shaft 9 so that thepad 5, and with it the workpiece, is pressed against the knife cylinder2.

The workpiece carrier, or staking frame comprises a frame-like structure17 at the front edge of which there is provided a clamping device (notshown in drawing) for the workpiece which clamping device can beoperated by means of a handle 18 (Fig. 2). In rigid connection with theframe 17 there are guide members 19 and 20 which permit verticalreciprocation of the frame while at the same time positively preventingany tilting of the frame. These guide members 19, 20 are guided insliding bushes 21, 22 attached to a fixed frame 23 positioned forexample on the axis of symmetry of the machine. Instead of the .twoguides 19, 20 shown in the drawings, there may be provided withadvantage three such guides for the staking frame so that, in additionto the guide members 19 there are two guide members 20. The arrangementthen forms a three-point suspension system for the staking frame andthereby ensures a particularly positively guided frame.

The operation that is to say the vertical reciprocation, of the stakingframe 17 is effected by means of a'hydraulic cylinder (see, moreespecially, Fig; which is located inside the guide member 19. The saidcylinder comprises an external tubular sleeve 24 and an internal plungerrod 25. The sleeve 24 and plunger rod 25 are respectively rotatably andpivotally connected through ball-and-socket joints 26 and 27 with theguide member 19, and thereby with the staking frame and the machineframe respectively; in this manner ensuring that any inaccuracy in themanufacture or assembly of the com ponent parts of the machine have nodisadvantageous efiect on the efiective operation of the machine. Inaddition, the provision of the said ball-and-socket joints cn ables acertain degree of inaccuracy, due to normal wear and tear, to bepositively compensated.

The hydraulic system operating the working cylinders described aboveconsists of two pressure pumps located in a common housing 28 butfunctioning independently, the common drive of which is provided by anelectric motor 29. The suction sides of both pumps are joined to acommon suction pipe 39 connected with a pressure liquid tank 31. Thepressure sides of the two pumps, on the other hand, are separatelyconnected as will be hereinafter described.

In operating the staking frame 17 the pressure liquid performs thefollowing cycle:

The pressure liquid for example oil, delivered from the pressure side 32of the relevaut'pump flows normally through a control valve 33 in itsopen or non-operated position, through pipes 34 and 3S and is cycledback into the tank 31. The liquid pressure thereby generated in a branchpipe 36 leading to the working cylinder 24 is insuflicient to overcomethe weight of the staking frame. As a result the frame remain in therest position while the pump unit is working.

When the valve 33 is partially closed by depressing a hand control lever37, the restricted flow of the pressure liquid increases the pressureinside the pipes 34 and 36. According to the speed at which the valve 33is closed, the cylinder 24 of the staking frame cylinder moves up wardlyat a corresponding speed. During this movement, the pressure oil flows(see, more especially, Figv 5) from the pipe 36 via a bore 38 into alongitudinal bore 39 of the plunger rod 25. To ensure a smooth start aspecial damping device is provided inside the bore 39 and comprises anauxiliary plunger 40 which, in the bottom stationary position of theworking cylinder, covers slots 41 of the plunger rod 25 with itscylindrical surface and with a tappet-like extension 42 rests againstthe end 43 of the cylinder. The auxiliary plunger is constantly actedupon by a pressure spring 44, and the stroke of the plunger in theoutward direction is limited by a stop ring 45.

The damping device described above functions in the following manner:

When the control lever 37 of the staking frame operating valve 33 isdepressed, that is to say when the valve 33 is partially closed, theelements of the working cylinder are in the positions shown in Fig. 5.The pressure liquid flowing to the longitudinal bore 39 can thus reachthe cylinder chamber 47 only through a comparatively very small bore 16in the plunger 41!. The sleeve 2d will consequently at first verygradually move upwards. In this movement it is accompanied by theauxiliary plunger 40 under the pressure exerted upon it by the spring 44until the top edge of said auxiliary plunger comes to rest against thering 45. In the meantime, however, the auxiliary plunger 40 has alreadyincreasingly opened the slots 41 forming main channel for the liquid sothat the channel for the pressure liquid which had a very smallcross-section initially, is progressively increased during the firstphase of the plunger movement until movement the pressure liquid canflow only through the small bore 46, that is to say slowly.

On the return movement of the cylinder 24, and beforethe bottom positionis reached, the damping device becomes likewwise operative as a resultof which the staking frame settles gently, under its own Weight, on therest provided for it on the machine frame.

Very similar conditions obtain in connection with the hydraulic systemoperating the working cylinder 12, 13,. which, as explained above,actuates the pressure device. This working cylinder is shown in Fig. lin an intermediate position and in Fig. 6 in the unoperative'position.it comprises a plunger 12 and a cylinder 13 provided with a guide bush13'. When the control valve 48 is open, that is to say when the controllever 54 is not depressed, the pressure oil coming from the pressureside 49 of the second pump unit circulates through pipe 5%), connection50, the ring channel 51 (Fig. 6), the connection 52' and the pipe 52,the open valve 48 and the pipe 53 back to the tank 31. When the controllever 54 is depressed closing the valve 48, the resulting increasedpressure forces the oil at first from the channel 51 through a smallbore 54 to the underside of the plunger $12 which latter is therebycaused to start to move smoothly, outwardly of the cylinder 13 at asuitably slow rate. As soon as the edge 55 of the plunger has uncoveredthe inlet for the pressure liquid, the plunger is placed gradually underfull pressure so that it moves outwards at speed, as and when required.A damping in the top position of the plunger is in this case generallynot required because the resilient leather pad 5, which rests, togetherwith the workpiece under suitable pressure against the knife cylinder,itself provides sufiicient damping. in order to enable the maximumdegree of contact pressurewhich, as is known, varies with the type ofleather or pelt to be workedto be adjusted, it is advantageous to limitthe top end of the stroke of the plunger 12 by a vertically adjustablestop 56. For this purpose the stop 56 can be provided with longitudinalslots 57, for fixing it in the adjusted position by means of screws 58.

In this case, too, the braking of the descending plunger 12 is effectedby means of the damping device described above which leaves only acomparatively small crosssection open for the pressure oilto passthrough. The plunger 12 returns to its inoperative position by thecounterweight 10 and also by its own weight and the weight of lever 10.

As has been mentioned above, the working cylinders operating the stakingframe and the pressure device are controlled through identical controlvalves by means of the control levers 37 and 54 respectively; as shownin Fig. 3, each of these levers is pivotally supported on the front wallof the machine frame by means of a pin 59. The power is transmitted tothe control valvcs-designated as complete units by 33 and 48respectively-by a rod 60 which is slidable in stationary guides 61, 62.To balance the weight of this linkage system and to compensate for thefriction generated by the guides, there is provided a pressure spring 63the initial tension of which can be adjusted by means of a threaded nut64. The length of the stroke of the linkage system canvbe adjusted ineither direction by means of milled nuts 65, 66.

With each linkage system 60 there is associated a control valve thedetails of which can be seen in Fig. 4. Essentially, such a valveconsists of a housing 67 having suitable unions 69, 63 for connecting tothe pipes supplying and entraining the pressure liquid respectively.Inside the valve there is a valve member 70, provided with a suitablesealing means, the head of the member being slidably received in apressure sleeve 71. The sleeve 71, in its turn, is slidable in a bore ofthe housing 67. The sleeve 71 eiiects sliding movement under the actionof a compression spring 72 and, when the control lever 33 or 48respectively is not depressed, the sleeve 71 rests with a shoulderformed in its surface engaging against a securing ring 73. Between ashoulder 74 on the valve member 70 and the underside of the pressuresleeve 71 a compression spring 75 is positioned. The unoperated positionof the valve member 70, as well as the moment when an excess-pressurepreventing device hereinafter de scribed is released, are adjusted bymeans of threaded nuts The operation of the control valve is as follows:

In the normal unoperated position of the control lever 37, or 54respectively (Fig. 3), the elements of the control valve are positionedas shown in Fig. 4, the valve member 70 not interrupting the channel 77so that pressure liquid can circulate freely, the linkage 60 being soadjusted by means of the spring 63 that there is a certain, small amountof play between the lower end portion 78 (Fig. 3) of the rod 60 and thetop end portion of the pressure sleeve 71. The adjusting nuts 76 or" thecontrol valve, together with the associated screw threaded top end ofthe valve member 70 are positioned within a bore 79 of the linkage 60,the diameter of said bore being large enough to allow sutficient freedomof movement for the nuts and the threaded end of the valve member 70.

When the control lever 37 or 54 respectively is depressed the movementof the linkage 60 is transmitted through the pressure sleeve 71 and thecompression spring 75 to the valve member 70 which is thereby caused tomove downwards and partially to restrict the cross-section of thechannel 77.

When the control lever 33 is released upwardly the valve member 70 isreturned to its normal position by the pressure of the liquid acting onthe lower end thereof and, more especially, by the return spring 72.

In the arrangement described above the spring 75 also preventsexcess-pressure becausewith the pump connected and the control leverkept down permanently-the pressure of the liquid becomes so great thatit can overcome the pressure of the spring 75 and in so doing it pushesthe valve member 70 upwards relative to the pressure sleeve 71, theadjusting nuts 76 and the associated threaded end of the valve member 70entering in the bore 79 of the linkage 60.

What I claim is:

l. A universal staking machine having a rotating knife cylinder, a'resilient pressure device for the workpiece capable of being pressedagainst the knife cylinder, and a workpiece holder or staking framecapable of vertical reciprocation, means for operating the pressuredevice and the workpiece holder hydraulically including individualcylinders, 21 separate pressure liquid circulating system for each ofsaid cylinders and throttle valve means controlling each system.

2. A universal staking machine having a rotating knife cylinder, aresilient pressure device for the workpiece capable of being pressedagainst the knife cylinder, and a workpiece holder or staking framecapable of vertical reciprocation, means for operating the pressure.device and the workpiece holder hydraulically including individualcylinders, a separate pressure liquid circulating system for each ofsaid cylinders and throttle valve means controlling each system, thestaking frame being actuated by a single working cylinder located on theaxis of symmetry of the said frame which is secured against tilting byguide members.

3. A universal staking machine having a rotating knife cylinder, aresilient pressure device for the workpiece capable of being pressedagainst the knife cylinder, and a workpiece holder or staking framecapable of vertical reciprocation, means for operating the pressuredevice and the workpiece holder hydraulically including individualcylinders, a separate pressure liquid circulating system for each ofsaid cylinders and throttle valve means controlling each system, thestaking frame being guided in stationary bearing bushes serving assliding guides for guide rods attached to the staking frame, as well asfor a tubular sleeve surrounding the operating cylinder of the stakingframe.

4. A staking machine as claimed in claim 1, wherein the valve member ofa control valve controlling operation of a cylinder is connected with acontrol lever, a compression spring being interposed between the valvemember and the lever and serves as a device preventing excesspressure,and the length of the stroke of the control lever being adjustable bymeans of stops.

5. A universal staking machine as claimed in claim 1, wherein a slidableand lockable stop is provided for regulating the top position of theoperating cylinderfor the pressure device.

6. A universal staking machine according to claim 1, wherein a dampingdevice is provided for the operating cylinder of the staking framecomprises an auxiliary plunger slidably guided within a hollow plungerrod, and acted upon by a spring and cooperating with channel openings ofthe plunger rod, the said auxiliary plunger being guided close to thebottom position of the cylinder by means of a tappet from the end of thecylinder and so designed as to open a small channel opening located inthe auxiliary plunger itself for the pressure liquid to pass through,while at the same time partially covering channel openings in theplunger rod.

7. A staking machine as claimed in claim 1, wherein the operatingcylinders are connected at either end by means of ball-and-socket jointsto the machine frame and to the member to be actuated respectively.

8. A staking machine as claimed in claim 1, wherein the valve member ofa control valve controlling operation of a cylinder is connected with acontrol lever, 21 compression spring being interposed between the valvemember and the lever and serves as a device preventing excesspressure.

No references cited.

